Automatic Piler

The Automatic piler is a logistics building used to stack and unstack items on Conveyor Belts and through Sorters, increasing effective transport capacity without changing the belt tier itself. It was added in patch 0.9.24.11182. Stacked cargo is treated as a single item by belts, Sorters, and even the Fractionator, which makes the building especially valuable anywhere items need to move in bulk.

An Automatic piler has one input and one output, with the sloped side indicating the direction of stacking or unstacking. When items enter from the smaller side, the building combines matching items into stacks. When items enter from the larger side, it breaks stacks back down. Two consecutive items of the same type can become a stack, and stacks can be combined further up to a maximum of four items per stack. A double-stack becomes two single items when unstacked, a four-stack becomes two double-stacks, and a three-stack becomes a double-stack plus a single item.

Automatic pilers can be stacked on top of one another. The baseline building limit is 7, and Vertical Construction upgrades increase that limit by 3 per level up to a maximum of 25. This makes them easy to integrate into compact logistics setups without requiring much floor space.

They are most useful in the early and mid game for extending the range of lower-tier belts and reducing material cost. For example, transport that would normally require MK.III Conveyor Belt can be done with MK.II or even MK.I by inserting one or more pilers to increase cargo density. They also improve the usefulness of lower-tier Sorters, since a sorter can move a whole stack instead of a single item, greatly increasing throughput.

A particularly efficient trick is to combine pilers with belt-speed changes. By feeding a faster belt into a piler and then outputting to a slower belt before piling again, a four-stack can be created with only two Automatic pilers instead of the usual three. This is especially useful for Hydrogen supply lines feeding Fractionators, where high throughput matters and long-distance transport with cheaper belts is desirable. Dropping from MK.III to MK.II reduces total throughput, but dropping from MK.II to MK.I does not, making that combination especially practical.

In the late game, Automatic pilers are less essential once Station Integrated Logistics and Pile Sorter Upgrade are available, because logistics stations and production buildings can output stacked cargo directly. Even then, they remain useful for optimizing Fractionator loops and for players who prefer belt-based logistics over station-based transport. If a downstream section of the line would otherwise become congested, the piler will naturally begin to work as cargo backs up; if the line is never saturated, the building simply will not need to operate. When merging piled and non-piled lines, make sure the non-piled side enters first so the flow does not stall.